<template>
  <div id="app">
     <div class="box">
       <div class="left"></div>
       <div class="middle"></div>
       <div class="right"></div>
     </div>
  </div>
</template>

<script>


export default {
  name: 'App',
  components: {
    
  }
}
</script>

<style lang="less" >
#app {
  .box {
    width: 100%;
    height: 100vh;
    display: flex;
    background-color: violet;
    .left {
      flex: 1;
    }

    .middle {
      flex: 1;
      background-color: lightgreen;
    }

    .right {
      flex: 1;
    }
  }
}
</style>
